Antenna alignment device

ABSTRACT

A ring-shaped frangible member for maintaining the movable internal antenna &#39;&#39;&#39;&#39;dish&#39;&#39;&#39;&#39; of a guided missile in a boresighted position and thus prevent it from becoming misaligned during storage and handling. When the missile is launched, movement of the antenna breaks up the ring so that it offers no interference with normal operation.

United States Patent [191 Parcher 1 July 17, 1973 ANTENNA ALIGNMENT DEVICE Primary Examiner-Benjamin A. Borchelt Assistant Examiner-Richard E. Berger [75] Inventor. Michael S. Parcher,Camarillo,Cal|f. mmmey Howard J. ay, 0 a e Wa ner [73] Assignee: The United States of America as d Richard S, Sciascia represented by the Secretary oi the Navy, Washington, D.C. [22] Filed: May 24, 1971 [57] I ABSTRACT PP 148,258 A ring-shaped frangible member for maintaining the movable internal antenna dish of a guided missile in 52 us. Cl. 343/705, 343/872 a 'boresishted Position and thus prevent it r m c m- [51 Int. Cl. Ii0lq 1/28 s misaligned during Storage and handlins- When the 58 Field of Search 343/880, 757, 766, missile is launched, movement of the antenna breaks 343 g72 up the ring so that it offers no interference with normal operation. [56] References Cited UNITED STATES PATENTS 3 Cmms, 3 Figures 2,683,011 7/1954 Haggerty 343/880 X ANTENNA ALIGNMENT DEVICE BACKGROUND OF THE INVENTION Aircraft-carried missiles of the target-seeking type incorporating a movable internal dish antenna have this member positioned during assembly so that it is aligned with the missiles boresight axis. However, during storage and installation on the aircraft, as well as on captive flights before launching, environmental forces tend to disturb this antenna alignment, and, as a result, a condition known as head droop" results which renders the missile incapable of performing in a satisfactory manner.

In an attempt to solve this problem, it has been customary to hold the antenna in its boresighted position by trapping oil in the hydraulic actuators which control antenna movement. However, this has not been completely acceptable due to-the unpredictable oil leakage characteristics of individual missiles, especially when an extended time interval elapses between assembly and final launch.

SUMMARY OF THE INVENTION The present concept, in a preferred embodiment, comprises a ring-shaped member composed of readily frangible material, such as a foamed plastic, for example, similar to Dow No. 33 Styrofoam plastic, inserted within the missile radome after the latter has been re- STATEMENT OF THE OBJECTS OF THE INVENTION One object of the present invention, therefore, is to provide means for maintaining the movable internal antenna of a target-seeking missile in proper alignment prior to launch.

Another object of the invention is to provide means for preventing head droop in a device of the class described. r

A further object of the invention is to provide an antenna-alignment ring of the type described whichis broken up into fragments upon the initiation of antenna movement.

A still further object is to provide a pro-launch antenna-alignment device for missiles which is simple in design and of low cost, and which does not interfere with operation of the missile after the latter has been launched.

Other objects, advantages and novel fatures of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings wherein:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a longitudinal view, partly in section, of one type ofmissilc with the invention ring-installed thereon;

FIG. 2 is an enlarged sectional view of FIG. 1 taken along the line 2-2; and

FIG. 3 is a detailed partly sectional view of a portion of FIG. I, also showing in broken lines the manner in which antenna movement serves to break up the invention ring when the latter is no longer needed.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the drawings is illustrated an airborne missile of the target-seeking type, such missile being designated generally by the. reference numeral 10. It incorporates a removable radome 12 within which is located an antenna dish 14, the latter being oscillatable through a predetermined angle during missile flight, as depicted by the broken lines in FIG. 3. Antenna 14 is positioned during assembly so as to be aligned with the missiles boresight axis, as in FIG. 1, and it is desired that such alignment be maintained during transportation, storage, and captive flight aboard an aircraft prior to launch. Frequently, such antenna alignment is achieved by trapping of oil in the antennas hydraulic actuators (not shown). This expedient is not invariably satisfactory due to the possibility of leakage in the oil supply lines, and a condition known as head droop results which can have a detrimental effect on operation and in extreme cases cause a failure of the mission. In less serious instances, downloading of an otherwise service- I able missile is necessary.

In accordance with a preferred embodiment of the present invention, an antenna-positioning ring 16 is disposed between the outer periphery of antenna 14 and the inner surface of radome 12, This ring 16 is composed of some frangible material, such as a deformable foamed plastic, for example, as Styrofoam, which breaks up upon the initiation of antenna movement. In FIG. 3 of the drawings is shown by dashed lines the result of such antenna movement, the ring 16 being broken up into fragments 18.

The ring is installed-in the following manner:

The radome 12 is removed from missile l0, and the ring is inserted so as tobecome wedged in the tapered radome at a point where it' will'lie adjacent'the periphery of antenna 14 when the radome is replaced, after ensuring that the antenna 14' is boresighted (FIG. 3). I The ring will hold the antenna in place until the an-. tenna hydraulic system (if used) is activated and the antenna begins to move. At this point, the ring will be' crushed, and will break up into the pieces 18 in FIG. 3'. These fragments have been found to have no adverse effect on missileperformance from either a mechanical or electromagnetic standpoint. I I

The positioning ring of the present invention is thus quickly and easily installed, without tools, by unskilled personnel. It functions indefinitely while the missile is in storage and for many captive flights without change of characteristics.

A large number of Styrofoam compounds may be employed for the ring, the only requirement being that the ring break up readily when the antenna begins to move. One preferred composition is known as Dow No. 33 Styrofoam, which is a deformable foamed plastic. Dimensions will obviously depend on the particular missile with which it is tobe employed. One ring used successfully is 1 inch in width, 6 inches in insidediameter, and 7 inches in outside diameter at the rear, tapered to 6 7/8 inches in outside diameter at the front.

Tests for insertion loss attenuation showed a 0.3 db when dry and 0.5 db when soaked in head hydraulic fluid. If desired, the ring can be sprayed with a moisture-resistant compound.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

I claim:

1. In a missile of the target-seeking type having a radome and an antenna therewithin which is designed to oscillate following launch of said missile and which antenna is subject to displacement from an optimum boresighted position during storage and handling of said missile subsequent to assembly and prior to the launching thereof, thereby producing an adverse effect being composed of a deformable foam plastic material. =8 

1. In a missile of the target-seeking type having a radome and an antenna therewithin which is designed to oscillate following launch of said missile and which antenna is subject to displacement from an optimum boresighted position during stOrage and handling of said missile subsequent to assembly and prior to the launching thereof, thereby producing an adverse effect on missile performance, the improvement which comprises: means for maintaining said antenna in its boresighted position set during assembly until initiation of antenna movement at launch, said means being in the form of a member of frangible material located intermediate the periphery of said antenna and the inner surface of said radome, said member being designed to be broken up into fragments upon initiation of antenna movement.
 2. A member as set forth in claim 1, said member being of annular configuration.
 3. A member as set forth in claim 2, said member being composed of a deformable foam plastic material. 